[explore]only fetch View Samples data when needed

[junlincc]

Context -

Currently both results and samples are fetched when user expands Data panel. They are refetched when query params change. I'll try to optimize that so that Samples are fetched only when needed

I noticed that on current master, we send a request for samples not only when chart data changes, but every time we open a modal.

I think that the "View Samples" use case is fairly uncommon. Also note that it only needs to be reprocess when the filters are altered, changing metrics and other query parameters don't require re-fetching/re-rendering.

Originally posted by @mistercrunch in #11854 (comment)

cc: @kgabryje @mistercrunch

[ktmud]

The rendering performance is also not very great while the "View Samples" tab is open. Sorting that table and resizing the panes are almost unbearably slow. Even adding/removing a metric also becomes slow.

[ktmud]

And it stays slow even when I switched back to the View Results tab.

[kgabryje]

@ktmud Shall we open an issue for performance improvements?

[villebro]

The rendering performance is also not very great while the "View Samples" tab is open. Sorting that table and resizing the panes are almost unbearably slow. Even adding/removing a metric also becomes slow.

Oh that's what that was. I hit this yesterday and wondered why everything became so sluggish all of a sudden.

@ktmud Shall we open an issue for performance improvements?

Yeah, I think this is pretty important to fix, as the new layout will probably result in increased use of the Samples tab.